Use of Sentinel-2 Data to Improve Multivariate Tree Species Composition in a Forest Resource Inventory

Aerial-photo interpreted inventories of forest resources, including tree species composition, are valuable in forest resource management, but are expensive to create and can be relatively inaccurate. Because of differences among tree species in their spectral properties and seasonal phenologies, it...

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Autores principales: Jay R. Malcolm, Braiden Brousseau, Trevor Jones, Sean C. Thomas
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Publicado: MDPI AG 2021
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spelling oai:doaj.org-article:959c4540ac5c4b2da21f2a92fdbd9c852021-11-11T18:53:16ZUse of Sentinel-2 Data to Improve Multivariate Tree Species Composition in a Forest Resource Inventory10.3390/rs132142972072-4292https://doaj.org/article/959c4540ac5c4b2da21f2a92fdbd9c852021-10-01T00:00:00Zhttps://www.mdpi.com/2072-4292/13/21/4297https://doaj.org/toc/2072-4292Aerial-photo interpreted inventories of forest resources, including tree species composition, are valuable in forest resource management, but are expensive to create and can be relatively inaccurate. Because of differences among tree species in their spectral properties and seasonal phenologies, it might be possible to improve such forest resource inventory information (FRI) by using it in concert with multispectral satellite information from multiple time periods. We used Sentinel-2 information from nine spectral bands and 12 dates within a two-year period to model multivariate percent tree species composition in >51,000 forest stands in the FRI of south-central Ontario, Canada. Accuracy of random forest (RF) and convolutional neural network (CNN) predictions were tested using species-specific basal area information from 155 0.25-ha field plots. Additionally, we created models using the Sentinel-2 information in concert with the field data and compared the accuracy of these models and the FRI-based models by use of basal areas from a second (13.7-ha) field data set. Based on average R<sup>2</sup> values across species in the two field data sets, the Sentinel-FRI models outperformed the FRI, showing 1.5- and 1.7-fold improvements relative to the FRI for RF and 2.1- and 2.2-fold improvements for CNN (mean R<sup>2</sup>: 0.141–0.169 (FRI); 0.217–0.295 (RF); 0.307–0.352 (CNN)). Models created with the field data performed even better: improvements relative to the FRI were 2.1-fold for RF and 2.8-fold for CNN (mean R<sup>2</sup>: 0.169 (FRI); 0.356 (RF); 0.469 (CNN)). As predicted, R<sup>2</sup> values between FRI- and field-trained predictions were higher than R<sup>2</sup> values with the FRI. Of the 21 tree species evaluated, 8 relatively rare species had poor models in all cases. Our multivariate approach allowed us to use more FRI stands in model creation than if we had been restricted to stands dominated by single species and allowed us to map species abundances at higher resolution. It might be possible to improve models further by use of tree stem maps and incorporation of the effects of canopy disturbances.Jay R. MalcolmBraiden BrousseauTrevor JonesSean C. ThomasMDPI AGarticleremote sensingmultivariate tree species compositionSentinel-2forest resource inventoryrandom forestconvolutional neural networkScienceQENRemote Sensing, Vol 13, Iss 4297, p 4297 (2021)
institution DOAJ
collection DOAJ
language EN
topic remote sensing
multivariate tree species composition
Sentinel-2
forest resource inventory
random forest
convolutional neural network
Science
Q
spellingShingle remote sensing
multivariate tree species composition
Sentinel-2
forest resource inventory
random forest
convolutional neural network
Science
Q
Jay R. Malcolm
Braiden Brousseau
Trevor Jones
Sean C. Thomas
Use of Sentinel-2 Data to Improve Multivariate Tree Species Composition in a Forest Resource Inventory
description Aerial-photo interpreted inventories of forest resources, including tree species composition, are valuable in forest resource management, but are expensive to create and can be relatively inaccurate. Because of differences among tree species in their spectral properties and seasonal phenologies, it might be possible to improve such forest resource inventory information (FRI) by using it in concert with multispectral satellite information from multiple time periods. We used Sentinel-2 information from nine spectral bands and 12 dates within a two-year period to model multivariate percent tree species composition in >51,000 forest stands in the FRI of south-central Ontario, Canada. Accuracy of random forest (RF) and convolutional neural network (CNN) predictions were tested using species-specific basal area information from 155 0.25-ha field plots. Additionally, we created models using the Sentinel-2 information in concert with the field data and compared the accuracy of these models and the FRI-based models by use of basal areas from a second (13.7-ha) field data set. Based on average R<sup>2</sup> values across species in the two field data sets, the Sentinel-FRI models outperformed the FRI, showing 1.5- and 1.7-fold improvements relative to the FRI for RF and 2.1- and 2.2-fold improvements for CNN (mean R<sup>2</sup>: 0.141–0.169 (FRI); 0.217–0.295 (RF); 0.307–0.352 (CNN)). Models created with the field data performed even better: improvements relative to the FRI were 2.1-fold for RF and 2.8-fold for CNN (mean R<sup>2</sup>: 0.169 (FRI); 0.356 (RF); 0.469 (CNN)). As predicted, R<sup>2</sup> values between FRI- and field-trained predictions were higher than R<sup>2</sup> values with the FRI. Of the 21 tree species evaluated, 8 relatively rare species had poor models in all cases. Our multivariate approach allowed us to use more FRI stands in model creation than if we had been restricted to stands dominated by single species and allowed us to map species abundances at higher resolution. It might be possible to improve models further by use of tree stem maps and incorporation of the effects of canopy disturbances.
format article
author Jay R. Malcolm
Braiden Brousseau
Trevor Jones
Sean C. Thomas
author_facet Jay R. Malcolm
Braiden Brousseau
Trevor Jones
Sean C. Thomas
author_sort Jay R. Malcolm
title Use of Sentinel-2 Data to Improve Multivariate Tree Species Composition in a Forest Resource Inventory
title_short Use of Sentinel-2 Data to Improve Multivariate Tree Species Composition in a Forest Resource Inventory
title_full Use of Sentinel-2 Data to Improve Multivariate Tree Species Composition in a Forest Resource Inventory
title_fullStr Use of Sentinel-2 Data to Improve Multivariate Tree Species Composition in a Forest Resource Inventory
title_full_unstemmed Use of Sentinel-2 Data to Improve Multivariate Tree Species Composition in a Forest Resource Inventory
title_sort use of sentinel-2 data to improve multivariate tree species composition in a forest resource inventory
publisher MDPI AG
publishDate 2021
url https://doaj.org/article/959c4540ac5c4b2da21f2a92fdbd9c85
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AT seancthomas useofsentinel2datatoimprovemultivariatetreespeciescompositioninaforestresourceinventory
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